Valve for manual control of hydraulic cylinders



spf.s,197o V.T.THOMAS am. 3,527,250

VALVE FOR MANUAL CONTROL OF HYDRAULIC'CYLINDERS Filed May 24, 1968United States Patent O 3,527,250 VALVE FOR MANUAL CONTROL OF HYDRAULICCYLINDERS Vitas T. Thomas and Robert A. Lovdahl, Racine, Wis.,

assignors to Tomco, Inc., Racine, Wis., a corporation of Wisconsin FiledMay 24, 1968, Ser. No. 731,821 Int. Cl. Fb 15/18 U.S. Cl. 137--565 5Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Thisinvention relates to a control valve for a portable hydraulic pumpwherein the control valve is used to control the buildup of pressure toa hydraulic device, to maintain the pressure in the hydraulic device andto relieve the pressure in the hydraulic device. The control functionsin a valve of the type contemplated herein are normally accomplished bya valve actuating device including a threaded spool which is subjectedto the force of the high pressure hydraulic iiuid flowing through thehousing. At high operating pressures the force acting on the spoolincreases the friction on the threads of the spool to such an extentthat the spool sticks in the housing.

SUMMARY OF THE INVENTION The invention disclosed herein provides acontrol valve for a portable hydraulic pump having the functions of thevalve controlled by an actuating device which requires substantially thesame actuating force or torque regardless of the pressure of thehydraulic fluid in the control valve. More specifically, the controlvalve according to the invention comprises a housing having a main flowpassage and a return ow passage connected to bypass a check valve in themain ilow passage with a pair of check valves in the return passage toisolate a section of the return passage from the pressure of thehydraulic uid in the main flow passages. An actuating device is mountedin the housing for movement into the isolated section of the returnpassage to open one of the pair of check valves in the return passage torelieve the pressure in the main passage. This arrangement of theactuating device in the section isolated by the pair of check valvesprevents the force of the high pressure hydraulic fluid from acting onthe actuating device so that it can be rotated easily regardless of theoperating pressure in the main passage.

Other objects and advantages of the present invention will become morereadily apparent when read in connection with the accompanying drawingsin which:

FIG. l is a schematic view of the portable hydraulic pump.

FIG. 2 is a section View in elevation of the control valve.

DESCRIPTION OF THE PREFERRED EMBODIMENT Although the disclosure hereofis detailed and exact to enable those skilled in the art to practice theinvention, the physical embodiments herein disclosed merely eX- Cil rice

emplify the invention which is defined in the claims appended hereto.

Referring to FIG. l, the control valve 10 is shown mounted within ahousing 12 and connected by a pipeline 14 to a hydraulic pump 16 whichis driven by an electric motor 18 to pump hydraulic fluid from areservoir 20 through the control valve to a hydraulic device (not shown)through a pipeline 21. The motor 18 is connected to an electrical powersource (not shown) by electric lines L1-L2 through a normally openswitch 22. The control valve 10 is used to control the operation of themotor 18, to maintain pressure in the outlet line 21, and to relieve thehydraulic pressure in pipeline 21 to the hydraulic device.

More particularly, the control valve 10, as seen in FIG. 2, includes ahousing or body 24 having a main ow passage 26 connected at the inletend to the pipeline 14 by a threaded nipple 17 and at the outlet end tothe pipeline 21 by a threaded nipple 23. Return flow of fluid throughthe passage 26 is prevented by means of a main check valve 28 having aball 30 biased into engagement with a valve seat 34 in the passage 26 bya spring 32 positioned between the ball 30 and the nipple 23. Hydraulicfluid is returned to the reservoir by means of a return or secondarypassage 40 connected to bypass the main check valve 28 in the mainpassage 26. The flow of fluid through passage 40 is controlled by meansof a rst return check valve 42 having a ball 44 biased into engagementwith a valve seat 48 provided in the return passage 40 by a spring 46positioned between the ball 44 and a threaded plug or retainer 50 havingan aperture 51. Hydraulic uid in the main passage 26 is prevented fromowing through the return passage 40 by means of a second return checkvalve 52 having a ball 54 biased into engagement with a valve seat 56provided in the return passage 40i by a spring 58 positioned between theball 52 and a threaded plug 60. Valves 42 and 52 are oppositely biasedand seated in passage 40 in a space relation.

The check valve 42 is opened to allow hydraulic fluid to bypass checkvalve 28 and return to the reservoir 20 by means of an actuating device62 mounted in a recess 64 connected to the section of return passage 40isolated by the check valves 42 and 52. More particularly, the actuatingdevice 62 includes a spool 66 having a needle 68 which projects intoreturn passage 40 in a position for engagement with the ball 44. Thecheck valve 42 is opened by moving the spool 66 axially into engagementwith ball 44 to move the ball 44 oil of the valve seat 48. This isaccomplished by providing a threaded section 70` on the spool `66 whichengages a threaded section 72 in the recess 64. Rotation of the spool 66in the recess 64 will move the needle 68 either toward or away from theball 44. The spool 66 is sealed in the recess 64 by means of an O- ringseal 74 provided in a groove 76 in the spool 66 with a plastic backupring 78 provided in the groove 76 to prevent extrusion of the O-ring.The spool is rotated by means of a handle `80 secured to a stem `82 onthe end of the spool `66 by means of a pair of pins 84 passing through apair of sleeves connected to an actuating lever 86. The actuating lever86 is positioned to engage switch 22 to control the operation of themotor 18 and pump 16. A pair of springs 88 are attached to the ends ofthe lever `8.6 to hold the lever in a neutral position with the switch22 open and the return check valve `42 closed.

`In operation, the handle 80` is rotated counterclockwise in FIG. 1, tomove the actuating lever 86 into engagement with the switch 22. Thiswill start the motor 18 and pump 16 to force hydraulic fluid throughline 14 and passage 26 in housing 10. The pressure of the hydrauliciluid will open check valve 28. The hydraulic fluid is prevented fromentering the return passage 40 by check valves 42 and 52. The handle 86Vis held in this position until the pressure-in the outletpipeline .21reaches the desired level. When the handle is released, springs 88rotate the actuating device 62 clockwise to a neutral position. Checkvalves 28 and 42 will both be closed and the pressure of the hydraulicuid in the outlet line 21 will be maintained at the desired level.'Rotation of the handle 80 clockwise will move the spool 66 into thehousing 10 and the needle 68 will engage and unseat the ball 44 from thevalve seat 48 against the bias of spring 46. The hydraulic fluid in theline 26 will flow past check valve 42 and will open the check valve 52allowing the hydraulic iluid to flow back to the reservoir through thepipeline 14 and pump 16. v

With this arrangement, the spool 66 is never subjected to the pressureof the hydraulic uid in passage 26 while hydraulic uid is being pumpedthrough the control valve or while the pressure of the hydraulic fluidis being maintained in the outlet line 21. In the absence of anyhydraulic pressure on the spool, it can be rotated freely and will neverlock in the housing.

What is claimed is:

1. A control valve for a hydraulic pump, said valve comprising ahousing, a main flow passage through said housing, a main valve in saidmain flow passage, a return fiow passage connected to said main flowpassage to bypass said main valve, a first return valve in said returnpassage, a second return valve in said return passage, and a threadedspool having a needle positioned in said return passage for engagementwith one of said return valves, said one of said return valves beingresiliently biased toward a closed position and arranged to relievepressure in said main flow passage when engaged and opened by the rotarymotion of said threaded spool in one direction.

2. A control valve according to claim 1 wherein said oneV of Ysaidreturn valves-comprises a one-way check valve positioned to prevent thereturn o'w of uid through said return passage and said other of saidreturn valves comprises a one-way check valve positioned to prevent theflow of hydraulic uid in a forward ydirection through said return flowpath.

3. A control valve according to claim 2 wherein said needle ispositioned for movement in said return passage between said first andsecond return |valves.

4. A control valve according to claim 1 including a hydraulic pumpconnected to said main flow passage, a normally opened switch connectedto control said pump, and an actuating lever connected to said spool andpositioned to engage and close said switch when said spool is in theother direction.

5. A control valve according to claim 4 including a spring positioned tobias said actuating lever and spool to a neutral position with saidswitch open and said rst return valve closed.

References Cited UNITED STATES PATENTS 869,755 10/1907 Tretch 137-599 XR911,285 2/1909 Barber. 1,577,446 3/ 1926 Brown 137-599 XR 2,342,3112/1944 Thompson. 2,518,212 8/1950 Wilson 137-599 XR 3,126,795 3/1964Kesselring 137-599 XR ROBERT G. NILSON, Primary Examiner U.S. C1. X.R.

